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382 lines
11 KiB
C++
382 lines
11 KiB
C++
/*
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* ac3strm_in.c: AC3 Audio strem class members handling scanning and
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* buffering raw input stream.
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*
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* Copyright (C) 2001 Andrew Stevens <andrew.stevens@philips.com>
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* Copyright (C) 2000,2001 Brent Byeler for original header-structure
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* parsing code.
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*
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of version 2 of the GNU General Public License
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* as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*/
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#include <config.h>
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#include <math.h>
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#include <stdlib.h>
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#include "audiostrm.hh"
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#include "outputstream.hh"
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#define AC3_SYNCWORD 0x0b77
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#define AC3_PACKET_SAMPLES 1536
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/// table for the available AC3 bitrates
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static const unsigned int ac3_bitrate_index[32] =
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{
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32, 40, 48, 56, 64, 80, 96, 112, 128, 160, 192,
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224, 256, 320, 384, 448, 512, 576, 640,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
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};
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static const unsigned int ac3_frame_size[3][32] =
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{
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{64, 80, 96, 112, 128, 160, 192, 224, 256, 320, 384,
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448, 512, 640, 768, 896, 1024, 1152, 1280,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
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{69, 87, 104, 121, 139, 174, 208, 243, 278, 348, 417,
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487, 557, 696, 835, 975, 1114, 1253, 1393,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
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{96, 120, 144, 168, 192, 240, 288, 336, 384, 480, 576,
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672, 768, 960, 1152, 1344, 1536, 1728, 1920,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
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};
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/// table for the available AC3 frequencies
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static const unsigned int ac3_frequency[4] = { 48000, 44100, 32000, 0 };
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AC3Stream::AC3Stream (IBitStream & ibs, OutputStream & into):
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AudioStream (ibs, into)
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{
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}
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bool
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AC3Stream::Probe (IBitStream & bs)
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{
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return bs.getbits (16) == AC3_SYNCWORD;
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}
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/*************************************************************************
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*
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* Reads initial stream parameters and displays feedback banner to users
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* @param stream_num AC3 substream ID
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*************************************************************************/
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void
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AC3Stream::Init (const int stream_num)
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{
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unsigned int framesize_code;
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this->stream_num = stream_num;
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MuxStream::Init (PRIVATE_STR_1, 1, // Buffer scale
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default_buffer_size,
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muxinto.vcd_zero_stuffing,
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muxinto.buffers_in_audio, muxinto.always_buffers_in_audio);
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mjpeg_info ("Scanning for header info: AC3 Audio stream %02x", stream_num);
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InitAUbuffer ();
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AU_start = bs.bitcount ();
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if (bs.getbits (16) == AC3_SYNCWORD) {
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num_syncword++;
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bs.getbits (16); // CRC field
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frequency = bs.getbits (2); // Sample rate code
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framesize_code = bs.getbits (6); // Frame size code
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framesize = ac3_frame_size[frequency][framesize_code >> 1];
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framesize = (framesize_code & 1) && frequency == 1 ? (framesize + 1) << 1 : (framesize << 1);
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size_frames[0] = framesize;
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size_frames[1] = framesize;
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num_frames[0]++;
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access_unit.start = AU_start;
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access_unit.length = framesize;
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bit_rate = ac3_bitrate_index[framesize_code >> 1];
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samples_per_second = ac3_frequency[frequency];
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/* Presentation time-stamping */
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access_unit.PTS = static_cast < clockticks > (decoding_order) *
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static_cast < clockticks > (AC3_PACKET_SAMPLES) *
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static_cast < clockticks > (CLOCKS) / samples_per_second;
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access_unit.DTS = access_unit.PTS;
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access_unit.dorder = decoding_order;
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++decoding_order;
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aunits.append (access_unit);
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} else {
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mjpeg_error ("Invalid AC3 Audio stream header.");
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exit (1);
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}
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OutputHdrInfo ();
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}
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/// @returns the current bitrate
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unsigned int
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AC3Stream::NominalBitRate ()
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{
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return bit_rate;
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}
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/// Prefills the internal buffer for output multiplexing.
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/// @param frames_to_buffer the number of audio frames to read ahead
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void
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AC3Stream::FillAUbuffer (unsigned int frames_to_buffer)
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{
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unsigned int framesize_code;
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last_buffered_AU += frames_to_buffer;
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mjpeg_debug ("Scanning %d MPEG audio frames to frame %d", frames_to_buffer, last_buffered_AU);
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static int header_skip = 5; // Initially skipped past 5 bytes of header
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int skip;
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bool bad_last_frame = false;
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while (!bs.eos () &&
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decoding_order < last_buffered_AU) {
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skip = access_unit.length - header_skip;
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if (skip & 0x1)
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bs.getbits (8);
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if (skip & 0x2)
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bs.getbits (16);
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skip = skip >> 2;
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for (int i = 0; i < skip; i++) {
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bs.getbits (32);
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}
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prev_offset = AU_start;
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AU_start = bs.bitcount ();
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if (AU_start - prev_offset != access_unit.length * 8) {
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bad_last_frame = true;
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break;
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}
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/* Check we have reached the end of have another catenated
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stream to process before finishing ... */
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if ((syncword = bs.getbits (16)) != AC3_SYNCWORD) {
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if (!bs.eos ()) {
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mjpeg_error_exit1 ("Can't find next AC3 frame - broken bit-stream?");
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}
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break;
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}
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bs.getbits (16); // CRC field
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bs.getbits (2); // Sample rate code TOOD: check for change!
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framesize_code = bs.getbits (6);
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framesize = ac3_frame_size[frequency][framesize_code >> 1];
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framesize = (framesize_code & 1) && frequency == 1 ? (framesize + 1) << 1 : (framesize << 1);
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access_unit.start = AU_start;
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access_unit.length = framesize;
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access_unit.PTS = static_cast < clockticks > (decoding_order) *
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static_cast < clockticks > (AC3_PACKET_SAMPLES) *
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static_cast < clockticks > (CLOCKS) / samples_per_second;;
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access_unit.DTS = access_unit.PTS;
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access_unit.dorder = decoding_order;
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decoding_order++;
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aunits.append (access_unit);
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num_frames[0]++;
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num_syncword++;
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#ifdef DEBUG_AC3_HEADERS
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/* Some stuff to generate frame-header information */
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printf ("bsid = %d\n", bs.getbits (5));
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printf ("bsmode = 0x%1x\n", bs.getbits (3));
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int acmode = bs.getbits (3);
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printf ("acmode = 0x%1x\n", acmode);
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if ((acmode & 0x1) && (acmode != 1))
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printf ("cmixlev = %d\n", bs.getbits (2));
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if ((acmode & 0x4))
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printf ("smixlev = %d\n", bs.getbits (2));
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if (acmode == 2)
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printf ("dsurr = %d\n", bs.getbits (2));
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printf ("lfeon = %d\n", bs.getbits (1));
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printf ("dialnorm = %02d\n", bs.getbits (5));
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int compre = bs.getbits (1);
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printf ("compre = %d\n", compre);
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if (compre)
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printf ("compr = %02d\n", bs.getbits (8));
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int langcode = bs.getbits (1);
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printf ("langcode = %d\n", langcode);
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if (langcode)
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printf ("langcod = 0x%02x\n", bs.getbits (8));
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while (bs.bitcount () % 8 != 0)
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bs.getbits (1);
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header_skip = (bs.bitcount () - AU_start) / 8;
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#endif
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if (num_syncword >= old_frames + 10) {
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mjpeg_debug ("Got %d frame headers.", num_syncword);
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old_frames = num_syncword;
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}
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}
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if (bad_last_frame) {
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mjpeg_error_exit1 ("Last AC3 frame ended prematurely!\n");
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}
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last_buffered_AU = decoding_order;
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eoscan = bs.eos ();
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}
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/// Closes the AC3 stream and prints some statistics.
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void
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AC3Stream::Close ()
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{
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stream_length = AU_start >> 3;
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mjpeg_info ("AUDIO_STATISTICS: %02x", stream_id);
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mjpeg_info ("Audio stream length %lld bytes.", stream_length);
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mjpeg_info ("Syncwords : %8u", num_syncword);
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mjpeg_info ("Frames : %8u padded", num_frames[0]);
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mjpeg_info ("Frames : %8u unpadded", num_frames[1]);
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bs.close ();
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}
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/*************************************************************************
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OutputAudioInfo
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gibt gesammelte Informationen zu den Audio Access Units aus.
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Prints information on audio access units
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*************************************************************************/
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void
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AC3Stream::OutputHdrInfo ()
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{
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mjpeg_info ("AC3 AUDIO STREAM:");
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mjpeg_info ("Bit rate : %8u bytes/sec (%3u kbit/sec)", bit_rate * 128, bit_rate);
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if (frequency == 3)
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mjpeg_info ("Frequency : reserved");
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else
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mjpeg_info ("Frequency : %d Hz", ac3_frequency[frequency]);
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}
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/**
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Reads the bytes neccessary to complete the current packet payload.
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@param to_read number of bytes to read
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@param dst byte buffer pointer to read to
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@returns the number of bytes read
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*/
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unsigned int
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AC3Stream::ReadPacketPayload (uint8_t * dst, unsigned int to_read)
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{
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static unsigned int aus = 0;
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static unsigned int rd = 0;
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unsigned int bytes_read = bs.read_buffered_bytes (dst + 4, to_read - 4);
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rd += bytes_read;
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clockticks decode_time;
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unsigned int first_header = (new_au_next_sec || au_unsent > bytes_read)
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? 0 : au_unsent;
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// BUG BUG BUG: how do we set the 1st header pointer if we have
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// the *middle* part of a large frame?
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assert (first_header <= to_read - 2);
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unsigned int syncwords = 0;
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unsigned int bytes_muxed = bytes_read;
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if (bytes_muxed == 0 || MuxCompleted ()) {
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goto completion;
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}
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/* Work through what's left of the current AU and the following AU's
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updating the info until we reach a point where an AU had to be
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split between packets.
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NOTE: It *is* possible for this loop to iterate.
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The DTS/PTS field for the packet in this case would have been
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given the that for the first AU to start in the packet.
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*/
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decode_time = RequiredDTS ();
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while (au_unsent < bytes_muxed) {
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// BUG BUG BUG: if we ever had odd payload / packet size we might
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// split an AC3 frame in the middle of the syncword!
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assert (bytes_muxed > 1);
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bufmodel.Queued (au_unsent, decode_time);
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bytes_muxed -= au_unsent;
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if (new_au_next_sec)
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++syncwords;
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aus += au->length;
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if (!NextAU ()) {
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goto completion;
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}
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new_au_next_sec = true;
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decode_time = RequiredDTS ();
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};
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// We've now reached a point where the current AU overran or
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// fitted exactly. We need to distinguish the latter case
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// so we can record whether the next packet starts with an
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// existing AU or not - info we need to decide what PTS/DTS
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// info to write at the start of the next packet.
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if (au_unsent > bytes_muxed) {
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if (new_au_next_sec)
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++syncwords;
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bufmodel.Queued (bytes_muxed, decode_time);
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au_unsent -= bytes_muxed;
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new_au_next_sec = false;
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} else // if (au_unsent == bytes_muxed)
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{
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bufmodel.Queued (bytes_muxed, decode_time);
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if (new_au_next_sec)
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++syncwords;
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aus += au->length;
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new_au_next_sec = NextAU ();
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}
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completion:
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// Generate the AC3 header...
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// Note the index counts from the low byte of the offset so
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// the smallest value is 1!
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dst[0] = AC3_SUB_STR_0 + stream_num;
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dst[1] = syncwords;
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dst[2] = (first_header + 1) >> 8;
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dst[3] = (first_header + 1) & 0xff;
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return bytes_read + 4;
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}
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/*
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* Local variables:
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* c-file-style: "stroustrup"
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* tab-width: 4
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* indent-tabs-mode: nil
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* End:
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*/
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